TABLE OF CONTENTS A simple and generally accepted definition of the term nanoelectronic device does not exist. In most cases, however, this term is applied to devices which have an important component that lies in the nanometer scale. When taking the development of the MOS technology as an example, the ambiguity of this definition becomes apparent. Almost since the beginning of MOS technology, the thickness of the gate isolator has been in the nanometer scale (about 100 nm in the 1980s, and less than 10 nm nowadays [1]). MOS transistors had not been considered as nanoelectronic devices until the channel length had reached a value less than 100 nm. This has happened only recently. In the case of the quantum dot laser, all the dimensions of the device exceed the nanometer scale while the quantum dots embedded into the active layer of the laser diode have nanoscale dimensions. Since these quantum dots the site where radiative recombination takes place are the most important component of the quantum dot laser, this laser is referred to as a nanoelectronic device.
Applying the definition given above, all the other quantum effect devices can also be considered as nanoelectronic devices, in principle. As an example of this class of devices, we will review the state-of-the-art of the resonant tunneling diode (RTD). It is the most simple quantum effect device with regard to its structure and enables high frequency and ultrafast digital electronic applications. Furthermore, the quantum cascade laser (QCL) is reviewed, which is used...
